This invention relates generally to a final drive assembly for a vehicle such as a track-type tractor.
Final drives for track-type tractors are known which have a first reduction gear group including an input pinion gear and intermeshing bull gear, and a second reduction gear group which is a planetary gear transmission. A sun gear shaft is driven by the bull gear and provides the input to the planetary transmission, and the ring gear of the planetary is fixed so that the planet gears drive the planet carrier member and the sprocket. Heretofor, this construction has exhibited several problems. Firstly, the sun gear shaft has been supported in such a manner that loads from the bull gear are undesirably transmitted through the sun gear and to the rolling bearings of the planet gears. Secondly, the sun gear shaft has been supported in such a manner that it could not be axially removed for servicing without substantially complete disassembly of the final drive. And thirdly, many final drives require that the sprocket be removed in order to disassemble and inspect the planetary gear transmission or to axially withdraw the sun gear shaft, and this requires that the track entrained about the sprocket be disassembled at additional expense.